Antimicrobial activity of the synthetic peptide Lys-a1 against oral streptococci

► The MIC values ranged from 3.9 to 125 μg mL−1, while the MBC values ranged from 3.9 to 500 μg mL−1. ► The peptide Lys-a1 demonstrated the potential to inhibit biofilm formation in all bacterial species tested. ► Streptococcus parasanguinis showed the greatest susceptibility to the peptide, reducing the number of viable cells at 1.9 μg mL−1. ► The antimicrobial peptide Lys-a1 has shown remarkable antimicrobial and antibiofilm activity.